title: Propionic acidemia and optic neuropathy: a report of two cases.
abstract: BACKGROUND
  Propionic acidemia is a metabolic disease produced by a deficiency of the enzyme propionyl-CoA carboxylase. It can lead to coma, with severe neurologic encephalopathy or present later in life with vomiting, hypotonia, and seizures. An early diagnosis with adequate treatment helps to prevent the sequelae. Among the described complications is optic neuropathy, although not commonly reported, it is very disabling.
  
  
  OBJECTIVE
  To describe two patients with propionic acidemia and optic neuropathy.
  
  
  METHODS
  Patient 1: 16 years old, male, parents without consanguinity. He was diagnosed at 5 months of age because of hypotonia and seizures. Until the age of 9 years, he evolved satisfactorily; therefore, he stopped treatment. At 13 years, he presented bilateral optic neuropathy. Patient 2: 20 years, female, parents without consanguinity. She was diagnosed with PA at 11 months of age because of hypotonia and seizures. She evolved satisfactorily until the age of 9 years when she presented a metabolic decompensation followed by a bad metabolic control. At 18 years, she presented bilateral progressive optic neuropathy.
  
  
  RESULTS
  Both patients have psychometric scores with borderline IQ 84-75 (WISC-R) beside optic neuropathy. They were evaluated by an ophthalmologist and also by neuroimaging (MRI of optic pathway).
  
  
  CONCLUSIONS
  Pathophysiology of optic neuropathy is not completely understood. There is evidence that the damage is due to an accumulation of neurotoxic compounds secondary to the metabolic block increasing the oxidative stress. We suggest an annual ophthalmologic evaluation in the long-term follow-up of organic acidurias with visual loss, in order to detect this disabling sequela at an earlier stage.
authors.affiliation: Laboratory of Genetics and Metabolic Diseases, Institute of Nutrition and Food Technology, (INTA) University of Chile, El Líbano 5524, Santiago, 7830490, Chile, carias@inta.uchile.cl.
authors.forename: Carolina
authors.initials: C
authors.lastname: Arias
authors.forename: Erna
authors.initials: E
authors.lastname: Raimann
authors.forename: Pilar
authors.initials: P
authors.lastname: Peredo
authors.forename: Juan Francisco
authors.initials: JF
authors.lastname: Cabello
authors.forename: Gabriela
authors.initials: G
authors.lastname: Castro
authors.forename: Alf
authors.initials: A
authors.lastname: Valiente
authors.forename: Alicia
authors.initials: A
authors.lastname: de la Parra
authors.forename: Paulina
authors.initials: P
authors.lastname: Bravo
authors.forename: Cecilia
authors.initials: C
authors.lastname: Okuma
authors.forename: Verónica
authors.initials: V
authors.lastname: Cornejo